Actuators and buttons have found recent widespread use in a variety of applications including remote controls and controllers associated with gaming consoles like the Sony® PlayStation® and Microsoft® Xbox®. A remote control or game controller can include one or more control assemblies. The control assemblies, in turn, include actuators and circuitry to convert a mechanical movement applied to the actuator by a user into an electrical signal. Directional pads (D-pads) are one example of control assemblies found on nearly all modern game controllers. D-pads typically comprise a substantially circular control surface, pivoted in the center and coupled to four buttons or switches associated with corresponding four primary directions.
FIGS. 1a and 1b illustrate a D-pad 100 used in a remote control 102 and a game controller 104, respectively. The D-pad 100 includes four buttons 106a-d and 108a-d associated with corresponding Up, Down, Right, and Left primary directions. To define secondary directions more easily, we will alternatively refer to the Up, Down, Left, and Right primary directions as North (N), South (S), East (E), and West (W), respectively. The compass points are merely used here as a convenience to define the directions and do not refer to actual compass points or cardinal directions.
Depressing the button 106a in the Up or N direction, for example, closes the underlying switch generating a corresponding electronic signal provided to the D-pad's circuitry (not shown). Similarly and for another example, depressing button 106b in the Down or S direction closes the underlying switch generating a corresponding electronic signal and providing it to the D-pad's circuitry (not shown). Simultaneously depressing both button 106a in the Up and N direction and button 106b in the Left or W direction closes both underlying switches, generating a corresponding electronic signal. The D-pad can sense movement in four primary directions (Up or N, Down or S, Right or E, and Left or W) and in four secondary directions (NE, NW, SE, and SW). The D-pad can sense movement in the four secondary directions when a user depresses two buttons. For example, the D-pad would determine movement in the NW direction when a user depresses both the Up or N and Left or W buttons.
D-pads 100 are relatively inexpensive to manufacture but typically lack angular resolution better than 45 degrees. And D-pads 100 do not measure the depression force with which the user presses the buttons 106a-d and 108a-d. If the D-pad 100 could measure the depression force, this could be used to control the rate of a cursor's movement.
To control the rate of a cursor's movement, some game controllers use a strain gauge or a force sensing resistor (FSR) to sense a force applied to the cursor buttons. An example of a FSR device is the IBM Trackpoint®, a small red button found on IBM® laptops. Similar FSR devices are in use in several other applications. FSR devices offer the advantage of providing control of both the direction and speed of cursor motion (which is a function of the depression force with which the user presses the buttons) in a relatively small form factor, and direction resolution is much improved compared with a D-pad. Although capable of providing excellent cursor control in a relatively small form factor, strain gauges or FSR devices are expensive to manufacture.